tpm: Move the LPC TPM driver to a subdirectory

This moves the LPC TPM driver to drivers/pc80/tpm so it can
be turned into a ramstage driver with a chip.h

It includes no other changes yet.

BUG=chrome-os-partner:33385
BRANCH=samus,auron
TEST=emerge-samus coreboot

Change-Id: Iac83e52db96201f37a0086eae9df244f8b8d48d9
Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Commit-Id: be2db391f9da80b8b75137af0fe81dc4724bc9d1
Original-Change-Id: I60ddd1d2a3e72bcf169a0b44e0c7ebcb87f4617d
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/226660
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9468
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

3 files changed, 683 insertions, 0 deletions

diff --git a/src/drivers/pc80/tpm/Kconfig b/src/drivers/pc80/tpm/Kconfig
new file mode 100644
index 0000000000..fbb3b423f4
--- /dev/null
+++ b/src/drivers/pc80/tpm/Kconfig
@@ -0,0 +1,7 @@
+config LPC_TPM
+	bool
+	default n
+	help
+	  Enable this option to enable LPC TPM support in coreboot.
+
+	  If unsure, say N.
diff --git a/src/drivers/pc80/tpm/Makefile.inc b/src/drivers/pc80/tpm/Makefile.inc
new file mode 100644
index 0000000000..6f973e12f1
--- /dev/null
+++ b/src/drivers/pc80/tpm/Makefile.inc
@@ -0,0 +1 @@
+romstage-$(CONFIG_LPC_TPM) += tpm.c
diff --git a/src/drivers/pc80/tpm/tpm.c b/src/drivers/pc80/tpm/tpm.c
new file mode 100644
index 0000000000..c0429ddc9c
--- /dev/null
+++ b/src/drivers/pc80/tpm/tpm.c
@@ -0,0 +1,675 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2011 The Chromium OS Authors. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/*
+ * The code in this file has been heavily based on the article "Writing a TPM
+ * Device Driver" published on http://ptgmedia.pearsoncmg.com and the
+ * submission by Stefan Berger on Qemu-devel mailing list.
+ *
+ * One principal difference is that in the simplest config the other than 0
+ * TPM localities do not get mapped by some devices (for instance, by
+ * Infineon slb9635), so this driver provides access to locality 0 only.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <delay.h>
+#include <arch/io.h>
+#include <arch/byteorder.h>
+#include <console/console.h>
+#include <tpm.h>
+#include <arch/early_variables.h>
+
+#define PREFIX "lpc_tpm: "
+
+/* coreboot wrapper for TPM driver (start) */
+#define	TPM_DEBUG(fmt, args...)		\
+	if (CONFIG_DEBUG_TPM) {		\
+		printk(BIOS_DEBUG, PREFIX);		\
+		printk(BIOS_DEBUG, fmt , ##args);	\
+	}
+#define TPM_DEBUG_IO_READ(reg_, val_) \
+	TPM_DEBUG("Read reg 0x%x returns 0x%x\n", (reg_), (val_))
+#define TPM_DEBUG_IO_WRITE(reg_, val_) \
+	TPM_DEBUG("Write reg 0x%x with 0x%x\n", (reg_), (val_))
+#define printf(x...) printk(BIOS_ERR, x)
+
+#define readb(_a) (*(volatile unsigned char *) (_a))
+#define writeb(_v, _a) (*(volatile unsigned char *) (_a) = (_v))
+#define readl(_a) (*(volatile unsigned long *) (_a))
+#define writel(_v, _a) (*(volatile unsigned long *) (_a) = (_v))
+/* coreboot wrapper for TPM driver (end) */
+
+#ifndef CONFIG_TPM_TIS_BASE_ADDRESS
+/* Base TPM address standard for x86 systems */
+#define CONFIG_TPM_TIS_BASE_ADDRESS        0xfed40000
+#endif
+
+/* the macro accepts the locality value, but only locality 0 is operational */
+#define TIS_REG(LOCALITY, REG) \
+    (void *)(CONFIG_TPM_TIS_BASE_ADDRESS + (LOCALITY << 12) + REG)
+
+/* hardware registers' offsets */
+#define TIS_REG_ACCESS                 0x0
+#define TIS_REG_INT_ENABLE             0x8
+#define TIS_REG_INT_VECTOR             0xc
+#define TIS_REG_INT_STATUS             0x10
+#define TIS_REG_INTF_CAPABILITY        0x14
+#define TIS_REG_STS                    0x18
+#define TIS_REG_BURST_COUNT            0x19
+#define TIS_REG_DATA_FIFO              0x24
+#define TIS_REG_DID_VID                0xf00
+#define TIS_REG_RID                    0xf04
+
+/* Some registers' bit field definitions */
+#define TIS_STS_VALID                  (1 << 7) /* 0x80 */
+#define TIS_STS_COMMAND_READY          (1 << 6) /* 0x40 */
+#define TIS_STS_TPM_GO                 (1 << 5) /* 0x20 */
+#define TIS_STS_DATA_AVAILABLE         (1 << 4) /* 0x10 */
+#define TIS_STS_EXPECT                 (1 << 3) /* 0x08 */
+#define TIS_STS_RESPONSE_RETRY         (1 << 1) /* 0x02 */
+
+#define TIS_ACCESS_TPM_REG_VALID_STS   (1 << 7) /* 0x80 */
+#define TIS_ACCESS_ACTIVE_LOCALITY     (1 << 5) /* 0x20 */
+#define TIS_ACCESS_BEEN_SEIZED         (1 << 4) /* 0x10 */
+#define TIS_ACCESS_SEIZE               (1 << 3) /* 0x08 */
+#define TIS_ACCESS_PENDING_REQUEST     (1 << 2) /* 0x04 */
+#define TIS_ACCESS_REQUEST_USE         (1 << 1) /* 0x02 */
+#define TIS_ACCESS_TPM_ESTABLISHMENT   (1 << 0) /* 0x01 */
+
+/*
+ * Error value returned if a tpm register does not enter the expected state
+ * after continuous polling. No actual TPM register reading ever returns ~0,
+ * so this value is a safe error indication to be mixed with possible status
+ * register values.
+ */
+#define TPM_TIMEOUT_ERR			(~0)
+
+/* Error value returned on various TPM driver errors */
+#define TPM_DRIVER_ERR		(~0)
+
+ /* 1 second is plenty for anything TPM does.*/
+#define MAX_DELAY_US	(1000 * 1000)
+
+/*
+ * Structures defined below allow creating descriptions of TPM vendor/device
+ * ID information for run time discovery. The only device the system knows
+ * about at this time is Infineon slb9635
+ */
+struct device_name {
+	u16 dev_id;
+	const char * const dev_name;
+};
+
+struct vendor_name {
+	u16 vendor_id;
+	const char * vendor_name;
+	const struct device_name* dev_names;
+};
+
+static const struct device_name atmel_devices[] = {
+	{0x3204, "AT97SC3204"},
+	{0xffff}
+};
+
+static const struct device_name infineon_devices[] = {
+	{0x000b, "SLB9635 TT 1.2"},
+	{0xffff}
+};
+
+static const struct device_name nuvoton_devices[] = {
+	{0x00fe, "NPCT420AA V2"},
+	{0xffff}
+};
+
+static const struct device_name stmicro_devices[] = {
+	{0x0000, "ST33ZP24" },
+	{0xffff}
+};
+
+static const struct vendor_name vendor_names[] = {
+	{0x1114, "Atmel", atmel_devices},
+	{0x15d1, "Infineon", infineon_devices},
+	{0x1050, "Nuvoton", nuvoton_devices},
+	{0x104a, "ST Microelectronics", stmicro_devices},
+};
+
+/*
+ * Cached vendor/device ID pair to indicate that the device has been already
+ * discovered
+ */
+static u32 vendor_dev_id CAR_GLOBAL;
+
+static inline u8 tpm_read_status(int locality)
+{
+	u8 value = readb(TIS_REG(locality, TIS_REG_STS));
+	TPM_DEBUG_IO_READ(TIS_REG_STS, value);
+	return value;
+}
+
+static inline void tpm_write_status(u8 sts, int locality)
+{
+	TPM_DEBUG_IO_WRITE(TIS_REG_STS, sts);
+	writeb(sts, TIS_REG(locality, TIS_REG_STS));
+}
+
+static inline u8 tpm_read_data(int locality)
+{
+	u8 value = readb(TIS_REG(locality, TIS_REG_DATA_FIFO));
+	TPM_DEBUG_IO_READ(TIS_REG_DATA_FIFO, value);
+	return value;
+}
+
+static inline void tpm_write_data(u8 data, int locality)
+{
+	TPM_DEBUG_IO_WRITE(TIS_REG_STS, data);
+	writeb(data, TIS_REG(locality, TIS_REG_DATA_FIFO));
+}
+
+static inline u16 tpm_read_burst_count(int locality)
+{
+	u16 count;
+	count = readb(TIS_REG(locality, TIS_REG_BURST_COUNT));
+	count |= readb(TIS_REG(locality, TIS_REG_BURST_COUNT + 1)) << 8;
+	TPM_DEBUG_IO_READ(TIS_REG_BURST_COUNT, count);
+	return count;
+}
+
+static inline u8 tpm_read_access(int locality)
+{
+	u8 value = readb(TIS_REG(locality, TIS_REG_ACCESS));
+	TPM_DEBUG_IO_READ(TIS_REG_ACCESS, value);
+	return value;
+}
+
+static inline void tpm_write_access(u8 data, int locality)
+{
+	TPM_DEBUG_IO_WRITE(TIS_REG_ACCESS, data);
+	writeb(data, TIS_REG(locality, TIS_REG_ACCESS));
+}
+
+static inline u32 tpm_read_did_vid(int locality)
+{
+	u32 value = readl(TIS_REG(locality, TIS_REG_DID_VID));
+	TPM_DEBUG_IO_READ(TIS_REG_DID_VID, value);
+	return value;
+}
+
+/*
+ * tis_wait_sts()
+ *
+ * Wait for at least a second for a status to change its state to match the
+ * expected state. Normally the transition happens within microseconds.
+ *
+ * @locality - locality
+ * @mask - bitmask for the bitfield(s) to watch
+ * @expected - value the field(s) are supposed to be set to
+ *
+ * Returns 0 on success or TPM_TIMEOUT_ERR on timeout.
+ */
+static int tis_wait_sts(int locality, u8 mask, u8 expected)
+{
+	u32 time_us = MAX_DELAY_US;
+	while (time_us > 0) {
+		u8 value = tpm_read_status(locality);
+		if ((value & mask) == expected)
+			return 0;
+		udelay(1); /* 1 us */
+		time_us--;
+	}
+	return TPM_TIMEOUT_ERR;
+}
+
+static inline int tis_wait_ready(int locality)
+{
+	return tis_wait_sts(locality, TIS_STS_COMMAND_READY,
+	                    TIS_STS_COMMAND_READY);
+}
+
+static inline int tis_wait_valid(int locality)
+{
+	return tis_wait_sts(locality, TIS_STS_VALID, TIS_STS_VALID);
+}
+
+static inline int tis_wait_valid_data(int locality)
+{
+	const u8 has_data = TIS_STS_DATA_AVAILABLE | TIS_STS_VALID;
+	return tis_wait_sts(locality, has_data, has_data);
+}
+
+static inline int tis_has_valid_data(int locality)
+{
+	const u8 has_data = TIS_STS_DATA_AVAILABLE | TIS_STS_VALID;
+	return (tpm_read_status(locality) & has_data) == has_data;
+}
+
+static inline int tis_expect_data(int locality)
+{
+	return !!(tpm_read_status(locality) & TIS_STS_EXPECT);
+}
+
+/*
+ * tis_wait_access()
+ *
+ * Wait for at least a second for a access to change its state to match the
+ * expected state. Normally the transition happens within microseconds.
+ *
+ * @locality - locality
+ * @mask - bitmask for the bitfield(s) to watch
+ * @expected - value the field(s) are supposed to be set to
+ *
+ * Returns 0 on success or TPM_TIMEOUT_ERR on timeout.
+ */
+static int tis_wait_access(int locality, u8 mask, u8 expected)
+{
+	u32 time_us = MAX_DELAY_US;
+	while (time_us > 0) {
+		u8 value = tpm_read_access(locality);
+		if ((value & mask) == expected)
+			return 0;
+		udelay(1); /* 1 us */
+		time_us--;
+	}
+	return TPM_TIMEOUT_ERR;
+}
+
+static inline int tis_wait_dropped_access(int locality)
+{
+	return tis_wait_access(locality, TIS_ACCESS_ACTIVE_LOCALITY, 0);
+}
+
+static inline int tis_wait_received_access(int locality)
+{
+	return tis_wait_access(locality, TIS_ACCESS_ACTIVE_LOCALITY,
+	                       TIS_ACCESS_ACTIVE_LOCALITY);
+}
+
+static inline int tis_has_access(int locality)
+{
+	return !!(tpm_read_access(locality) & TIS_ACCESS_ACTIVE_LOCALITY);
+}
+
+static inline void tis_request_access(int locality)
+{
+	tpm_write_access(TIS_ACCESS_REQUEST_USE, locality);
+}
+
+static inline void tis_drop_access(int locality)
+{
+	tpm_write_access(TIS_ACCESS_ACTIVE_LOCALITY, locality);
+}
+
+/*
+ * PC Client Specific TPM Interface Specification section 11.2.12:
+ *
+ *  Software must be prepared to send two writes of a "1" to command ready
+ *  field: the first to indicate successful read of all the data, thus
+ *  clearing the data from the ReadFIFO and freeing the TPM's resources,
+ *  and the second to indicate to the TPM it is about to send a new command.
+ *
+ * In practice not all TPMs behave the same so it is necessary to be
+ * flexible when trying to set command ready.
+ *
+ * Returns 0 on success if the TPM is ready for transactions.
+ * Returns TPM_TIMEOUT_ERR if the command ready bit does not get set.
+ */
+static int tis_command_ready(u8 locality)
+{
+	u32 status;
+
+	/* 1st attempt to set command ready */
+	tpm_write_status(TIS_STS_COMMAND_READY, locality);
+
+	/* Wait for response */
+	status = tpm_read_status(locality);
+
+	/* Check if command ready is set yet */
+	if (status & TIS_STS_COMMAND_READY)
+		return 0;
+
+	/* 2nd attempt to set command ready */
+	tpm_write_status(TIS_STS_COMMAND_READY, locality);
+
+	return tis_wait_ready(locality);
+}
+
+/*
+ * Probe the TPM device and try determining its manufacturer/device name.
+ *
+ * Returns 0 on success (the device is found or was found during an earlier
+ * invocation) or TPM_DRIVER_ERR if the device is not found.
+ */
+static u32 tis_probe(void)
+{
+	const char *device_name = "unknown";
+	const char *vendor_name = device_name;
+	const struct device_name *dev;
+	u32 didvid;
+	u16 vid, did;
+	int i;
+
+	if (car_get_var(vendor_dev_id))
+		return 0;  /* Already probed. */
+
+	didvid = tpm_read_did_vid(0);
+	if (!didvid || (didvid == 0xffffffff)) {
+		printf("%s: No TPM device found\n", __FUNCTION__);
+		return TPM_DRIVER_ERR;
+	}
+
+	car_set_var(vendor_dev_id, didvid);
+
+	vid = didvid & 0xffff;
+	did = (didvid >> 16) & 0xffff;
+	for (i = 0; i < ARRAY_SIZE(vendor_names); i++) {
+		int j = 0;
+		u16 known_did;
+		if (vid == vendor_names[i].vendor_id) {
+			vendor_name = vendor_names[i].vendor_name;
+		} else {
+			continue;
+		}
+		dev = &vendor_names[i].dev_names[j];
+		while ((known_did = dev->dev_id) != 0xffff) {
+			if (known_did == did) {
+				device_name = dev->dev_name;
+				break;
+			}
+			j++;
+		}
+		break;
+	}
+	/* this will have to be converted into debug printout */
+	printf("Found TPM %s by %s\n", device_name, vendor_name);
+	return 0;
+}
+
+/*
+ * tis_senddata()
+ *
+ * send the passed in data to the TPM device.
+ *
+ * @data - address of the data to send, byte by byte
+ * @len - length of the data to send
+ *
+ * Returns 0 on success, TPM_DRIVER_ERR on error (in case the device does
+ * not accept the entire command).
+ */
+static u32 tis_senddata(const u8 * const data, u32 len)
+{
+	u32 offset = 0;
+	u16 burst = 0;
+	u32 max_cycles = 0;
+	u8 locality = 0;
+
+	if (tis_wait_ready(locality)) {
+		printf("%s:%d - failed to get 'command_ready' status\n",
+		       __FILE__, __LINE__);
+		return TPM_DRIVER_ERR;
+	}
+	burst = tpm_read_burst_count(locality);
+
+	while (1) {
+		unsigned count;
+
+		/* Wait till the device is ready to accept more data. */
+		while (!burst) {
+			if (max_cycles++ == MAX_DELAY_US) {
+				printf("%s:%d failed to feed %d bytes of %d\n",
+				       __FILE__, __LINE__, len - offset, len);
+				return TPM_DRIVER_ERR;
+			}
+			udelay(1);
+			burst = tpm_read_burst_count(locality);
+		}
+
+		max_cycles = 0;
+
+		/*
+		 * Calculate number of bytes the TPM is ready to accept in one
+		 * shot.
+		 *
+		 * We want to send the last byte outside of the loop (hence
+		 * the -1 below) to make sure that the 'expected' status bit
+		 * changes to zero exactly after the last byte is fed into the
+		 * FIFO.
+		 */
+		count = min(burst, len - offset - 1);
+		while (count--)
+			tpm_write_data(data[offset++], locality);
+
+		if (tis_wait_valid(locality) || !tis_expect_data(locality)) {
+			printf("%s:%d TPM command feed overflow\n",
+			       __FILE__, __LINE__);
+			return TPM_DRIVER_ERR;
+		}
+
+		burst = tpm_read_burst_count(locality);
+		if ((offset == (len - 1)) && burst)
+			/*
+			 * We need to be able to send the last byte to the
+			 * device, so burst size must be nonzero before we
+			 * break out.
+			 */
+			break;
+	}
+
+	/* Send the last byte. */
+	tpm_write_data(data[offset++], locality);
+
+	/*
+	 * Verify that TPM does not expect any more data as part of this
+	 * command.
+	 */
+	if (tis_wait_valid(locality) || tis_expect_data(locality)) {
+		printf("%s:%d unexpected TPM status 0x%x\n",
+		       __FILE__, __LINE__, tpm_read_status(locality));
+		return TPM_DRIVER_ERR;
+	}
+
+	/* OK, sitting pretty, let's start the command execution. */
+	tpm_write_status(TIS_STS_TPM_GO, locality);
+
+	return 0;
+}
+
+/*
+ * tis_readresponse()
+ *
+ * read the TPM device response after a command was issued.
+ *
+ * @buffer - address where to read the response, byte by byte.
+ * @len - pointer to the size of buffer
+ *
+ * On success stores the number of received bytes to len and returns 0. On
+ * errors (misformatted TPM data or synchronization problems) returns
+ * TPM_DRIVER_ERR.
+ */
+static u32 tis_readresponse(u8 *buffer, size_t *len)
+{
+	u16 burst_count;
+	u32 offset = 0;
+	u8 locality = 0;
+	u32 expected_count = *len;
+	int max_cycles = 0;
+
+	/* Wait for the TPM to process the command */
+	if (tis_wait_valid_data(locality)) {
+		printf("%s:%d failed processing command\n", __FILE__, __LINE__);
+		return TPM_DRIVER_ERR;
+	}
+
+	do {
+		while ((burst_count = tpm_read_burst_count(locality)) == 0) {
+			if (max_cycles++ == MAX_DELAY_US) {
+				printf("%s:%d TPM stuck on read\n",
+				       __FILE__, __LINE__);
+				return TPM_DRIVER_ERR;
+			}
+			udelay(1);
+		}
+
+		max_cycles = 0;
+
+		while (burst_count-- && (offset < expected_count)) {
+			buffer[offset++] = tpm_read_data(locality);
+			if (offset == 6) {
+				/*
+				 * We got the first six bytes of the reply,
+				 * let's figure out how many bytes to expect
+				 * total - it is stored as a 4 byte number in
+				 * network order, starting with offset 2 into
+				 * the body of the reply.
+				 */
+				u32 real_length;
+				memcpy(&real_length,
+				       buffer + 2,
+				       sizeof(real_length));
+				expected_count = be32_to_cpu(real_length);
+
+				if ((expected_count < offset) ||
+				    (expected_count > *len)) {
+					printf("%s:%d bad response size %d\n",
+					       __FILE__, __LINE__,
+					       expected_count);
+					return TPM_DRIVER_ERR;
+				}
+			}
+		}
+
+		/* Wait for the next portion */
+		if (tis_wait_valid(locality)) {
+			printf("%s:%d failed to read response\n",
+			       __FILE__, __LINE__);
+			return TPM_DRIVER_ERR;
+		}
+
+		if (offset == expected_count)
+			break;	/* We got all we need */
+
+	} while (tis_has_valid_data(locality));
+
+	/* * Make sure we indeed read all there was. */
+	if (tis_has_valid_data(locality)) {
+		printf("%s:%d wrong receive status: %x %d bytes left\n",
+		       __FILE__, __LINE__, tpm_read_status(locality),
+	               tpm_read_burst_count(locality));
+		return TPM_DRIVER_ERR;
+	}
+
+	/* Tell the TPM that we are done. */
+	if (tis_command_ready(locality) == TPM_TIMEOUT_ERR)
+		return TPM_DRIVER_ERR;
+
+	*len = offset;
+	return 0;
+}
+
+/*
+ * tis_init()
+ *
+ * Initialize the TPM device. Returns 0 on success or TPM_DRIVER_ERR on
+ * failure (in case device probing did not succeed).
+ */
+int tis_init(void)
+{
+	if (tis_probe())
+		return TPM_DRIVER_ERR;
+	return 0;
+}
+
+/*
+ * tis_open()
+ *
+ * Requests access to locality 0 for the caller. After all commands have been
+ * completed the caller is supposed to call tis_close().
+ *
+ * Returns 0 on success, TPM_DRIVER_ERR on failure.
+ */
+int tis_open(void)
+{
+	u8 locality = 0; /* we use locality zero for everything */
+
+	if (tis_close())
+		return TPM_DRIVER_ERR;
+
+	/* now request access to locality */
+	tis_request_access(locality);
+
+	/* did we get a lock? */
+	if (tis_wait_received_access(locality)) {
+		printf("%s:%d - failed to lock locality %d\n",
+		       __FILE__, __LINE__, locality);
+		return TPM_DRIVER_ERR;
+	}
+
+	/* Certain TPMs seem to need some delay here or they hang... */
+	udelay(10);
+
+	if (tis_command_ready(locality) == TPM_TIMEOUT_ERR)
+		return TPM_DRIVER_ERR;
+
+	return 0;
+}
+
+/*
+ * tis_close()
+ *
+ * terminate the current session with the TPM by releasing the locked
+ * locality. Returns 0 on success of TPM_DRIVER_ERR on failure (in case lock
+ * removal did not succeed).
+ */
+int tis_close(void)
+{
+	u8 locality = 0;
+	if (tis_has_access(locality)) {
+		tis_drop_access(locality);
+		if (tis_wait_dropped_access(locality)) {
+			printf("%s:%d - failed to release locality %d\n",
+			       __FILE__, __LINE__, locality);
+			return TPM_DRIVER_ERR;
+		}
+	}
+	return 0;
+}
+
+/*
+ * tis_sendrecv()
+ *
+ * Send the requested data to the TPM and then try to get its response
+ *
+ * @sendbuf - buffer of the data to send
+ * @send_size size of the data to send
+ * @recvbuf - memory to save the response to
+ * @recv_len - pointer to the size of the response buffer
+ *
+ * Returns 0 on success (and places the number of response bytes at recv_len)
+ * or TPM_DRIVER_ERR on failure.
+ */
+int tis_sendrecv(const uint8_t *sendbuf, size_t send_size,
+		 uint8_t *recvbuf, size_t *recv_len)
+{
+	if (tis_senddata(sendbuf, send_size)) {
+		printf("%s:%d failed sending data to TPM\n",
+		       __FILE__, __LINE__);
+		return TPM_DRIVER_ERR;
+	}
+
+	return tis_readresponse(recvbuf, recv_len);
+}